Dispersants and compositions thereof

A composition comprising (i) a particulate solid, wherein the particulate solid is a pigment, (ii) an organic medium, wherein the organic medium is an organic liquid or a plastics material;

• and (iii) a compound of Formula (1) and salts thereof:
• B—CO-Z-R Formula (1)
• wherein
• B comprises a hydrophobic alkyl chain, based on polyisobutylene with a number average molecular weight of 300-5000 which together with the —CO— group is the residue of a polyisobutylene succinic anhydride;
• Z is a divalent bridging group which is attached to the carbonyl group through an oxygen or nitrogen atom and represented by the formula:
• —N(T)-A- or —O-A-;
• wherein
• T is a hydrogen, or a C1-18 hydrocarbyl radical, or a group represented by A or the residue of the polyisobutylene succinic anhydride;
• A is an alkylene or hydroxyalkylene radical containing from 2-6 carbon atoms;
• R is a quaternary ammonium group represented by the formula:
• —N+(T2)(T3)(T4)W−
• wherein
• T2, T3 and T4 are each independently hydrogen, optionally substituted alkyl alkaryl or cycloalkyl groups, or R is a N-oxide functionalized quaternary ammonium group;
• and
• W− is a colourless or coloured anion.